Movie starlets, those delicate, orchid-like creatures, tend to be interviewed in five-star London hotel suites controlled by luxury air conditioning and hovering publicists.

Today, though, I find Gemma Arterton sat on set in rainy Newcastle, inside a battered trailer in a community centre car park and she seems right at home. ‘I grew up on a council estate,’ she says cheerily, ‘and this community centre is so sweet – like the one I used to go to for Brownies.’

Given her cut-glass accent and the fact that her on film debut was as the head girl in St Trinian’s, I tell Arterton I’d expected her roots to be, well, posher. ‘Are you joking?’ she cackles. ‘I grew up in Kent with an Estuary accent so strong it was almost Cockney. I was all like “wot the f*** are you lookin’ at?” until I went to “drrrrramah” school, where they told me that it wouldn’t do me any favours and they teach you RP [received pronunciation] instead.

‘I remember going to my dad’s house for Sunday roast and I said something like: ‘May you pass the ketchup?’ and he went: ‘F*** off, I’m not passing you nuffing when you speak like that. What are you, Mary Poppins, or somefing?’

She might not be Mary but there’s something of the breezy, young Julie Andrews à la The Sound Of Music about Arterton’s turn in Song For Marion. Her new film is a heart-warming British comedy – and the reason we are sitting in this car park today – that casts this adorably down-to-earth 27-year-old as an inspirational music teacher who volunteers to lead a hilarious OAP choir that includes acting legends Vanessa Redgrave and Terence Stamp.

‘I think it’s been the most challenging job I’ve ever done – apart from theatre stuff,’ she says earnestly. ‘I had to learn to play the piano in a month, plus I felt so responsible for the choir. They were mainly these lovely old people who’d been in choirs and some of them were a bit batty and they could get unruly, and I was trying to keep everyone together while doing my job.’

With her ebony hair, ridiculously pretty nose, a winning way with grumpy old people and the fact she’s not too posh to push a broom (her mum was a cleaner), I suddenly realise who Arterton reminds me of: Disney’s Snow White. I half expect bluebirds to fly through the trailer window and perch on her fingers.

But the joy of Arterton is that she’s not a goody two-shoes Hollywood princess. She may have got a Brownie badge for toy-making but admits she was ‘cheeky’ at school. ‘I was the joker,’ she recalls. ‘When I got into trouble, it was probably for making fart noises in class.’ A pleasure she’s never grown out of. ‘I think it’s the Gravesend girl in me,’ she giggles. ‘Obviously I’m very demure most of the time but I do love a filthy joke.’

Luckily so. Her ‘really filthy sense of humour’ is what led director Tommy Wirkola to cast her in Hansel & Gretel: Witch Hunters ahead of The Girl With The Dragon Tattoo’s Noomi Rapace and former Bond Girl Eva Green.

As an actress, Arterton, who already has a Bafta Rising Star nomination to her credit, prefers to ‘do big/small, big/small’ when it comes to picking movies. Balancing out action blockbusters such as Prince Of Persia and Quantum Of Solace (she played a blink-and-miss Bond Girl called Strawberry Fields) with interesting low-budget indies such as The Disappearance Of Alice Creed, Tamara Drewe and now Song For Marion.

This year, however, she’s made a new resolution. ‘I’ve decided to shun the “big” side for a bit,’ she says. ‘Over Christmas, I turned down this huge, very commercial film – I can’t tell you which but it’s one of those feel-good family films you know is going to be a massive smash but I felt this unease about doing it.’

Why? It sounds fun. ‘I think that I’m… I’m…’ she hesitates, carefully, looking worried. I want to hug her. ‘It’s delicate in that it’s this bizarre line where you have be a bit of a “name” to get the financing for the smaller films but if you don’t have the respect and credentials as an actor, you probably won’t get asked to do the really covetable roles.

‘I want to work with good directors and good writers and do really unusual things. You can’t sit on the fence in this job. You have to be strong.’

She tucks a bit of hair behind her left ear and I notice a tattoo. ‘It’s an angel wing,’ she reveals. ‘I thought it might be a bit vulgar to have it on both sides – so I’ve just got the one.’ Appropriate for an actress now boldly flying in just one direction.